Smart Self-Repairing System for Concrete Beams

联邦可持续发展战略是加拿大促进可持续发展的主要工具。它将可持续和有复原力的基础设施确定为关键的发展优先事项之一。国家对可持续发展的推动力引发了对开发适应机械和环境负荷的智能结构系统的研究工作的需求。智能结构模仿人类的肌肉和神经系统，其中系统及其相关组件形成一个实体，其行为模式模仿生物功能。建议的研究的目的是开发一个智能的自我修复系统，混凝土梁经历的缺陷（裂缝和过度变形），在正常的操作负载。 该系统是由形状记忆合金（SMA）线嵌入钢筋混凝土梁内，并连接到电流供应。SMA是一种智能材料，当受到通过电流施加的热量时往往会收缩。通过两端的机械锚固件约束材料将导致SMA中的张力的发展，从而产生后张效应。这种机制将通过拉动混凝土梁中裂缝的两侧来改善结构性能，并减小构件在外加载荷下的挠度。该系统的开发将分为三个连续阶段：系统设计、系统验证和系统可靠性。自修复系统的组成部分，包括材料表征，SMA锚固，应力损失和温度效应将在第一阶段通过小规模测试和数值模拟进行检查。与第一阶段有关的设计建议将输入第二阶段，在第二阶段中，将使用大规模测试、本构建模和数值模拟来验证受弯曲和剪切控制的梁的系统响应。第三阶段是关于检查使用该系统在现实生活中的混凝土框架的设计的可靠性。采用新技术的风险将使用结构可靠性方法进行量化，并与加拿大国家建筑规范的安全标准进行比较。 使用自修复技术建造的新混凝土结构在其使用寿命期间很可能不需要结构修复。这将降低我们基础设施的维护成本，根据下议院交通，基础设施和社区常务委员会2015年进行的一项研究结果，该成本占项目生命周期总成本的80%。实施新技术还可以减少在结构维护期间生产和安装加固材料所产生的碳足迹。随着对可持续发展领域专业工程师和研究人员需求的增加，毕业的HQP专业从事结构评估和维修的广泛领域对加拿大经济有利。

The Federal Sustainable Development Strategy is Canada's primary vehicle for sustainable development. It sets sustainable and resilient infrastructure as one of the key development priorities. The nation's drive for sustainability initiates the need to direct research efforts toward developing smart structural systems that adapt with mechanical and environmental loads. Smart structures mimic human muscular and nervous systems, where the system and its related component form an entity that behave in a pattern that emulates a biological function. The objective of the proposed research is to develop a smart self-repairing system for concrete beams experiencing deficiencies (cracks and excessive deformation) at normal operating loads. The system is composed of Shape Memory Alloy (SMA) wires embedded inside a reinforced concrete beam and connected to an electric current supply. The SMA is a smart material that tends to contract when subjected to heat applied via an electric current. Restraining the material by mechanical anchors at both ends will lead to the development of tension force in the SMA, and hence a post-tensioning effect. This mechanism will improve the structural performance by pulling the two sides of a crack in a concrete beam and reduce the member's deflection under applied loads. The system will be developed in three sequential stages; system design, system verification, and system reliability. The components of the self-repair system including material characterization, SMA anchorage , stress losses, and temperature effects will be examined in the first stage by small-scale testing and numerical simulation. The design recommendations pertaining to the first stage will feed into the second stage in which large scale-testing, constitutive modeling, and numerical simulation will be used to verify the system response for flexural- and shear-governed beams. The third stage is concerned with examining the reliability of using the system in the design of real-life concrete frames. The risk of adapting the new technology will be quantified using structural reliability methods and compared with the safety standards of the National Building Code of Canada. New concrete structures built with the self-repair technology will most likely not require structural repairs during their service life. This will reduce the maintenance cost of our infrastructure which accounts up to 80% of the total cost over the lifetime of the project as per the findings of a study conducted in 2015 by the Standing Committee on Transport, Infrastructure and Communities at the House of Commons. Implementing the new technology can also reduce the carbon footprint that result from producing and installing strengthening materials during structural maintenance. With the increased demand for professional engineers and researchers working in the field of sustainability, graduating HQP specialized in the broad area of structural assessment and repair is beneficial to the Canadian economy.